The invention relates to a method for the production of extrudates from regenerable raw materials using biopolymeric and mineral raw materials.
The use of pure biopolymers as building materials and fillers is known. Because of the negative properties of these building materials and fillers, particularly their inadequate mechanical and chemical load-carrying capabilities, and because of their high processing costs, their use is very limited.
The use of biopolymers, produced by agriculture and forestry, and the utilization of regenerable natural resources, are an economic requirement and the basis for extensive investigations in research and industry.
The German patent 32, 06 751, IPC C 08 L 3/02, discloses a method for producing foamed, gelatinized starch products, with which grainy or powdered starch or starch-containing materials are heated and extruded in the presence of 10-30% by weight of water and a gas-forming or gas-evolving blowing agent in an extrusion press to temperatures of 60.degree.-220.degree. C.
It is an object of the known solution to produce a foamed material from easily obtainable raw materials using a simple method and to use it in manifold ways in the same way known synthetic resin foams are used. Furthermore, the foamed material would also be suitable for food purposes. The solution has the disadvantage that mineral components are added as a blowing agent or, also as a blowing agent base. The raw materials, used for this purpose, require a prior, separate modification and/or cross-linking. The types of minerals used include calcium carbonate and sodium carbonate.